/*
  ==============================================================================

   This file is part of the JUCE framework.
   Copyright (c) Raw Material Software Limited

   JUCE is an open source framework subject to commercial or open source
   licensing.

   By downloading, installing, or using the JUCE framework, or combining the
   JUCE framework with any other source code, object code, content or any other
   copyrightable work, you agree to the terms of the JUCE End User Licence
   Agreement, and all incorporated terms including the JUCE Privacy Policy and
   the JUCE Website Terms of Service, as applicable, which will bind you. If you
   do not agree to the terms of these agreements, we will not license the JUCE
   framework to you, and you must discontinue the installation or download
   process and cease use of the JUCE framework.

   JUCE End User Licence Agreement: https://juce.com/legal/juce-8-licence/
   JUCE Privacy Policy: https://juce.com/juce-privacy-policy
   JUCE Website Terms of Service: https://juce.com/juce-website-terms-of-service/

   Or:

   You may also use this code under the terms of the AGPLv3:
   https://www.gnu.org/licenses/agpl-3.0.en.html

   THE JUCE FRAMEWORK IS PROVIDED "AS IS" WITHOUT ANY WARRANTY, AND ALL
   WARRANTIES, WHETHER EXPRESSED OR IMPLIED, INCLUDING WARRANTY OF
   MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, ARE DISCLAIMED.

  ==============================================================================
*/

namespace juce
{

BufferingAudioReader::BufferingAudioReader (AudioFormatReader* sourceReader,
                                            TimeSliceThread& timeSliceThread,
                                            int samplesToBuffer)
    : AudioFormatReader (nullptr, sourceReader->getFormatName()),
      source (sourceReader), thread (timeSliceThread),
      numBlocks (1 + (samplesToBuffer / samplesPerBlock))
{
    sampleRate            = source->sampleRate;
    lengthInSamples       = source->lengthInSamples;
    numChannels           = source->numChannels;
    metadataValues        = source->metadataValues;
    bitsPerSample         = 32;
    usesFloatingPointData = true;

    timeSliceThread.addTimeSliceClient (this);
}

BufferingAudioReader::~BufferingAudioReader()
{
    thread.removeTimeSliceClient (this);
}

void BufferingAudioReader::setReadTimeout (int timeoutMilliseconds) noexcept
{
    timeoutMs = timeoutMilliseconds;
}

bool BufferingAudioReader::readSamples (int* const* destSamples, int numDestChannels, int startOffsetInDestBuffer,
                                        int64 startSampleInFile, int numSamples)
{
    auto startTime = Time::getMillisecondCounter();
    clearSamplesBeyondAvailableLength (destSamples, numDestChannels, startOffsetInDestBuffer,
                                       startSampleInFile, numSamples, lengthInSamples);

    const ScopedLock sl (lock);
    nextReadPosition = startSampleInFile;

    bool allSamplesRead = true;

    while (numSamples > 0)
    {
        if (auto block = getBlockContaining (startSampleInFile))
        {
            auto offset = (int) (startSampleInFile - block->range.getStart());
            auto numToDo = jmin (numSamples, (int) (block->range.getEnd() - startSampleInFile));

            for (int j = 0; j < numDestChannels; ++j)
            {
                if (auto* dest = (float*) destSamples[j])
                {
                    dest += startOffsetInDestBuffer;

                    if (j < (int) numChannels)
                        FloatVectorOperations::copy (dest, block->buffer.getReadPointer (j, offset), numToDo);
                    else
                        FloatVectorOperations::clear (dest, numToDo);
                }
            }

            startOffsetInDestBuffer += numToDo;
            startSampleInFile += numToDo;
            numSamples -= numToDo;

            allSamplesRead = allSamplesRead && block->allSamplesRead;
        }
        else
        {
            if (timeoutMs >= 0 && Time::getMillisecondCounter() >= startTime + (uint32) timeoutMs)
            {
                for (int j = 0; j < numDestChannels; ++j)
                    if (auto* dest = (float*) destSamples[j])
                        FloatVectorOperations::clear (dest + startOffsetInDestBuffer, numSamples);

                allSamplesRead = false;
                break;
            }
            else
            {
                ScopedUnlock ul (lock);
                Thread::yield();
            }
        }
    }

    return allSamplesRead;
}

BufferingAudioReader::BufferedBlock::BufferedBlock (AudioFormatReader& reader, int64 pos, int numSamples)
    : range (pos, pos + numSamples),
      buffer ((int) reader.numChannels, numSamples),
      allSamplesRead (reader.read (&buffer, 0, numSamples, pos, true, true))
{
}

BufferingAudioReader::BufferedBlock* BufferingAudioReader::getBlockContaining (int64 pos) const noexcept
{
    for (auto* b : blocks)
        if (b->range.contains (pos))
            return b;

    return nullptr;
}

int BufferingAudioReader::useTimeSlice()
{
    return readNextBufferChunk() ? 1 : 100;
}

bool BufferingAudioReader::readNextBufferChunk()
{
    auto pos = (nextReadPosition.load() / samplesPerBlock) * samplesPerBlock;
    auto endPos = jmin (lengthInSamples, pos + numBlocks * samplesPerBlock);

    OwnedArray<BufferedBlock> newBlocks;

    for (int i = blocks.size(); --i >= 0;)
        if (blocks.getUnchecked (i)->range.intersects (Range<int64> (pos, endPos)))
            newBlocks.add (blocks.getUnchecked (i));

    if (newBlocks.size() == numBlocks)
    {
        newBlocks.clear (false);
        return false;
    }

    for (auto p = pos; p < endPos; p += samplesPerBlock)
    {
        if (getBlockContaining (p) == nullptr)
        {
            newBlocks.add (new BufferedBlock (*source, p, samplesPerBlock));
            break; // just do one block
        }
    }

    {
        const ScopedLock sl (lock);
        newBlocks.swapWith (blocks);
    }

    for (int i = blocks.size(); --i >= 0;)
        newBlocks.removeObject (blocks.getUnchecked (i), false);

    return true;
}


//==============================================================================
//==============================================================================
#if JUCE_UNIT_TESTS

static bool isSilent (const AudioBuffer<float>& b)
{
    for (int channel = 0; channel < b.getNumChannels(); ++channel)
        if (b.findMinMax (channel, 0, b.getNumSamples()) != Range<float>{})
            return false;

    return true;
}

struct TestAudioFormatReader : public AudioFormatReader
{
    explicit TestAudioFormatReader (const AudioBuffer<float>* b)
        : AudioFormatReader (nullptr, {}),
          buffer (b)
    {
        jassert (buffer != nullptr);
        sampleRate            = 44100.0f;
        bitsPerSample         = 32;
        usesFloatingPointData = true;
        lengthInSamples       = buffer->getNumSamples();
        numChannels           = (unsigned int) buffer->getNumChannels();
    }

    bool readSamples (int* const* destChannels, int numDestChannels, int startOffsetInDestBuffer,
                      int64 startSampleInFile, int numSamples) override
    {
        clearSamplesBeyondAvailableLength (destChannels, numDestChannels, startOffsetInDestBuffer,
                                           startSampleInFile, numSamples, lengthInSamples);

        if (numSamples <= 0)
            return true;

        for (int j = 0; j < numDestChannels; ++j)
        {
            static_assert (sizeof (int) == sizeof (float),
                           "Int and float size must match in order for pointer arithmetic to work correctly");

            if (auto* dest = reinterpret_cast<float*> (destChannels[j]))
            {
                dest += startOffsetInDestBuffer;

                if (j < (int) numChannels)
                    FloatVectorOperations::copy (dest, buffer->getReadPointer (j, (int) startSampleInFile), numSamples);
                else
                    FloatVectorOperations::clear (dest, numSamples);
            }
        }

        return true;
    }

    const AudioBuffer<float>* buffer;
};

static AudioBuffer<float> generateTestBuffer (Random& random, int bufferSize)
{
    AudioBuffer<float> buffer { 2, bufferSize };

    for (int channel = 0; channel < buffer.getNumChannels(); ++channel)
        for (int sample = 0; sample < buffer.getNumSamples(); ++sample)
            buffer.setSample (channel, sample, random.nextFloat());

    return buffer;
}

class BufferingAudioReaderTests final : public UnitTest
{
public:
    BufferingAudioReaderTests()  : UnitTest ("BufferingAudioReader", UnitTestCategories::audio)  {}

    void runTest() override
    {
        TimeSliceThread thread ("TestBackgroundThread");
        thread.startThread (Thread::Priority::normal);

        beginTest ("Reading samples from a blocked reader should produce silence");
        {
            struct BlockingReader final : public TestAudioFormatReader
            {
                explicit BlockingReader (const AudioBuffer<float>* b)
                    : TestAudioFormatReader (b)
                {
                }

                bool readSamples (int* const* destChannels,
                                  int numDestChannels,
                                  int startOffsetInDestBuffer,
                                  int64 startSampleInFile,
                                  int numSamples) override
                {
                    unblock.wait();
                    return TestAudioFormatReader::readSamples (destChannels, numDestChannels, startOffsetInDestBuffer, startSampleInFile, numSamples);
                }

                WaitableEvent unblock;
            };

            Random random { getRandom() };
            constexpr auto bufferSize = 1024;

            const auto source = generateTestBuffer (random, bufferSize);
            expect (! isSilent (source));

            auto* blockingReader = new BlockingReader (&source);
            BufferingAudioReader reader (blockingReader, thread, bufferSize);

            auto destination = generateTestBuffer (random, bufferSize);
            expect (! isSilent (destination));

            read (reader, destination);
            expect (isSilent (destination));

            blockingReader->unblock.signal();
        }

        beginTest ("Reading samples from a reader should produce the same samples as its source");
        {
            Random random { getRandom() };

            for (auto i = 4; i < 18; ++i)
            {
                const auto bufferSize = 1 << i;
                const auto source = generateTestBuffer (random, bufferSize);
                expect (! isSilent (source));

                BufferingAudioReader reader (new TestAudioFormatReader (&source), thread, bufferSize);
                reader.setReadTimeout (-1);

                auto destination = generateTestBuffer (random, bufferSize);
                expect (! isSilent (destination));
                expect (source != destination);

                read (reader, destination);
                expect (source == destination);
            }
        }
    }

private:
    void read (BufferingAudioReader& reader, AudioBuffer<float>& readBuffer)
    {
        constexpr int blockSize = 1024;

        const auto numSamples = readBuffer.getNumSamples();
        int readPos = 0;

        for (;;)
        {
            reader.read (&readBuffer, readPos, jmin (blockSize, numSamples - readPos), readPos, true, true);

            readPos += blockSize;

            if (readPos >= numSamples)
                break;
        }
    }
};

static BufferingAudioReaderTests bufferingAudioReaderTests;

#endif

} // namespace juce
